Automatic switching system



Aug. 21, 1928. 1,681,158

A. E. ANDERSON AUTOMATIC SWITCHING SYSTEM Filed April 28, '1927 1 y J r0 E $0 U) r .7 as 9 -53 L 14 ,0 H

Inventor:

A'P'vid EAnderson, y m

HIS Attorney.

Registered Aug. 21, 1928.

U NIT D ST ATE S series.

ARVID E. ANDERSON, or soo'rrA; NEW YORK, AssIGNoR TO GENERAL ELECTRICCOMPANY, A CORPORATION OF NEW YORK.

AUTOMATIC SWITCHING SYSTEM.

. Application filed April 28,

My-invention relates to automatic switch. ing systems, and particularlyto switching systems forselectively controlling the connections betweena load circuit and two alterlatingcurrent sources and its object istoprovide an improved switching system of this particular kind.

In systems of distribution iii-which a load circuit is normallysuppliedby a preferred source of current when the conditions of thatsource. are normal and an emergency source of current is':arranged .to'supply current to the loadcircuitwhen the preferred source fails, itisdesirable to reconnect the. preferred source,- when it isreenergizechfto the load circuit -befre' the emergency source is dis--connected therefrom in orde'rthat the supply of currentto the loadcircuit may not be interruptedwhen-the transfer is made. .In accordancewith one feature OfJmyinVentiOn I provide an arrangementwhereby thepreferred source, when reenergized while the cmcrgency'source issupplying current to tho load circuit, is not reconnected to the loadvcircuit until a predetermined phase'rclation occurs between thevoltagesof the tw'o sources so that when the two sources are connected togetheran excessive circulating-current does not flow between the two sources.My invention will be better understood from the following descriptiontaken in conmotion with the accompanying drawing and its scope willpointed out in the appended claims. v

Referring to the accompanying drawing, which is a diagram of anautomaticswitching system for selectively controlling the coir nections betweenaload circuit, a. preferred source of currentand an emergency source ofcurrent. 1 and 2-represents two sources of current. shown'as supplycircuits, whichare adapted to be connected to a load circuit 3 by thecircuit breakers 4 and 5 respectively which maybe o-fanysuitable type,examples of which are well known inthe art. As shown the circuitbreakers 4 and 5 are ofthe well known latched-in type and are providedwith the closing coils'G and 7 respectively andthe trip coils' S and 9respectively.

10 and 11 are voltage relays which are adapted tobe energized from thepreferred and the emergency sourcesrespectively. The voltage relay 10has acontrol relay'12 associated therewith which is arranged to be energized when the voltage relay 10-i's ener 1927. Serial No. 187,402.

relay 11 is energized a predetermined amount. Y i

and thejvoltagerelay 10 is deenergized. The control relays'12 and 13 arepreferably timedelay relays so that they do not function until aftertheir coils have been energized acertain length Of time In-this mannermomentary changes in thevoltagesof the sources do not effect unnecessaryopenings and closings of the circuit breakers.

In order that eithersource may be. employed as the'preferred source achange-over switch 15 is provided which isadapted-when moved todifferent positions .to' change the connections of the-various: controldevices to accomplish this result. i lVhen .the changeover switch 15"isin. itsaleft -ha'nd position the source 2 is the preferred source andsource 1 is the emergency source. and when; the change-over 15 is in itsright-hand position the source 1 is the preferredsource and the source 2is the emergency source. I 1

In order to effectthei closing of thecircuit breaker associated with thepreferred source when it is reenergized,..-I provide an auto maticsynchronizing. device--16jwhich is -arranged to operate to effect theclosing of the preferred circuit.- breaken when i a. predetermined phaserelation Occurs between the voltages of the two sources 1 and 2.Thislsynchronizing device may be of any. suitable type, examples ofwhich are well known in the art. If the sources 1 and 2 are connectedtogether at some other point so-that their frequencies arcthe same butthe phases of their voltages at the points where they are connected tothe load circuit. may differ from each other, itis preferable to havethe syn-. chronizing. device 16 arranged so that it closes its cont-acts17 only when. thephase difference remains less than acertain amount formore 'than .a predetermined length of'time. *If the sources 1 and 2 areindependent sources so that they may differ in frequencies as well asphase-it is=preferable in that case to use a synchronizing device whichalso functions in accordance with the frequency difference. ---Such adevice'is shown in Letters Patent-Reissue 16 ,540 to O. C. Travel. Sincethe'particular construction of' the synchronizing'device forms no partof my invention I have not shown the device in detail.

In order to effect the reclosing of the circuit breaker associated withthe preferred source in case it is reenergized and the automaticsynchronizingdeyice 16 fai ls to function within a predetermined time;provide a time relay 18 which is arranged to eflect first the opening ofthe circuit brc-akerj-iassociated" with the emergency source and thenthe closing of the circuit breaker associated with the preferred source.7

19 and 20 are control -r'elays of'the well known 'hesitating type whichcontrol the circuits ofthe'clo'singcoils 6 and 7 respectively. 21 and'22- are control transformers which are connected respectively to thesources l and'2 and which supply current to the 'various con'=- trol deiicess Since "it is aisually desirabl *to} have'any ipping action due toover-current trans ferried-to the gene'rating' stationj breaker, thecircuit-breakers 4 an'd"5 are preferably pro vided with over-current-protection which functions onlyiin ease of a'fvery severe oven loadwhichfw'arren-ts'thef lockingoutof the= circuit breakers. #I-n the'drawing'f I-have shown-an oyerloadiela'y 23"which-i'sconnect ed to'thelo'ad circuit'j3 by a currenttransformer 24i The overload rel'ay23controls the circuit of alocli o'ut' relay 26which'1s arranged-in anysuitable manner, examples-- of which are'wellknown' in the a'rt so thatit remains inits energized position after its coil is deenergizeduntilit is reset by hand. The coil of the 1ock-out-re1ay '26 is arran ed tobe connected inseri'es with the trip'cml 8 and contacts 27- of relay 23if the circuit breaker 4is closedwben the overload relay 23 isoperatedand to be connected inseries with the trip coil '9 and'contacts'28 of relay 23 if thecircuit'breaker-5 is closed-when theoverload relay 23'is operated. "The lock-out relay 26 when in itsenergized position-prevents the circuit of both closing coilsfrom beingcompleted.-

The-operation 'ofthe system-shown is as follows :It' will beassumed-that the change over switch 15 is inits left-hand position, thatboth ofthe circuitbreakers 4 and -5 are open, and that both 'ofthe'sources 1 and 2 are ene rgized simultaneously. The relay 10- isconnected across the secondary of the transformer 22'by contacts 33 and34 of the changeover switch 15 so that the relay is. energized by thevoltageof the preferred source 2-. By closing its contacts 35, the relay1O completes the circu'itof the coilof the time-relay12- acrossthe'secondary'of-the transformer 22 through contacts 33 and 34 of thechange-over switch 15. The relay 11 is connected across the secondary'ofthe transformer 21 by con tacts 36 and 37 of tlie'change over switch sothat the relay is ener zed by the emergency source-1. By closing-itscontacts 38 the relay 11 closes contacts in the circuit of the timerelay13 but the circuit of this time-relay is open at this time at thecontacts 39. of the relay 10. Therefore only the time relay 12 isenergized long enough to close its contacts when both sourcesaresimultaneously.enerr The coils 40 and 41 of the synchronizing device16 are alsocpnnected across the secondaries of the transformer 22 and 21respectively by the contacts-33,34, and 36, 37 so that the synchronizingdevice is operative to close its contacts-17 'when-the -predeterminedphase relation between-'thevoltages ofi-the two sourcesoccurs.'=Preferably'the time delay of the synchronizing device 16-=-is longerthan, the time delay of relays 12 so'that it does not have time to closeits; contacts 17' before the preferred circuit breaker is closed.

' After a predetermined'time,relay12-closes its contacts 42,there'byzcompleti ilga. circuit-y for the hesitating control relay 2O 1to :efi'ect the completion of the circuit :0f:tl1'e=0l0sing,--'- coil7;" Thecircuit of theicontro-laaelay20 is frombne side 'of a: suitablesource-of con-- trol current through theaauxiliar-y; scontacts 43 oncircuit breake'r5,1 coil 20, conductor. 44,; contacts 45 oflockout relay26 conductor-.46,

auxiliary contacts 47 on circuit breaker 4,

condu'ctor48, contacts-49 and 50 of 'change.

over switch 15, conductor'51, contacts 42 of relay .12 to the other sideof theI-eontrol source; The control relay- 2O3-by: closing its contacts52 completes the circuit. of= the closing coil 7 so.thatthercircuitbreaker 5 closes and connects the preferred source 2 to the load circuita 1 w 1 It will now'be. assumed-that while the circuit breaker 5'isclosedcandathe emergency. source 1 is ener ized the source 2 fails sothat the voltage reliiy; 10 opens its contacts 35,

which causesthe time relay 12 to bedeenergized, and'closes-its contacts39 so that the coil of the time-relay 13 is connected across thesecondary of the transformer 21$ After the coil of the relay 13 has beenenergized for apredeterinined length of-ti'mc, the relay 13 closes itscontacts 54-an'd completes a: circuit for the trip coil 9"so that thecircuit breaker 5; opens and disconnects the source 2 from theloadcircuit 3'. The circuit of the'trip coil 9: is from one side ,of asuit-, able source of control/current through aux-- iliary contacts 55on the'circuitbreaker 5,

trip coil 9, conductor 56, contacts; 57- and 58 As soon as the' 66and'67 of change-over switch 15, conductor 59, contacts 54 of relay 13to the other side of the source of control current. The relay 19 byclosing its contacts 68 completes the circ'uit of the closing coil 6 sothat the circuit breaker 4 closes and connects the source 1 to the loadcircuit 3.

It will be assumed now that while the emergency source 1 is supplyingcurrent to the load circuit 3 the ,voltage conditions of the preferredsource are restored'to-normal control relay 20. I This circuit'is fromone side of asuitable source of control current, through auxiliarycontacts 43 'on the circuit breaker 5, coil ofrelay20, conductor,44,contacts 45 of lock-out-r'elay 26, conductor-'46, contacts 69 and 70 ofchange-over switch 15, conductor 71, contacts 17 of synchronizing device16, conductor 51, contacts 42' of relay 12 to the other side'of thecontrol source, The energize tion of the 'hesit ating control relay2Oeffects the closing ofthe circuit breaker '5' inthe manner heretoforedescribed. The preferred source'2the'refore is reconnected'to the loadcircuit 3 before the emergency sourcel is disconnected therefrom. Whenthe circuit breaker 5 closes a circuit is completed for the trip coil 8of thecircuit'bre'aker 4 to effect'the opening of this circuit breakerand the disconnection'of the emergency source 1 from the load circuit 3.The circuit of the trip 7 i coil 8 is from one side of a suitable sourceof control current through auxiliary contacts 72 on the circuit breaker4, trip coil 8, con ductor 73, contacts 74 and 75 of. change-over switch15, conductor .76, auxiliary contacts '77 on circuit breaker 4,conductor 78, auxiliary contacts 79 on circuit breaker 5, conductor 51,contacts 42 of relay 12 tothe other side of the control source.

If for any reason the desired phase relation between the voltages of thetwo sources does not occur within a predetermined time after thepreferred source is reenergized the time relay 18, which hasa'relatively long time delay, operates to effect the opening of thecircuit breaker associated with the emergency source and the subsequentclosing of the circuit breaker associated with the pre ferred source.The circuit of the time-relay 18 is completed when the preferred circuitbreaker is open and the contacts 80 ofthe relay 12 are closed; Thiscircuit is from one side of a suitable source of control current throughauxiliary'contacts 43 on the circuit breaker 5, conductor 81, contacts82 and 83 of change-over switch 15, conductor-'84, coil of relay 18,contact 80 of relay 12-to the other side of the control source; Relay18'by closing its contacts 85 completes a circuit for the trip coil 8ofthe circuit breaker4 to effect the opening of the circuitbreaker.Thisci'r cuit isfrom one side of a suitable source of controlcurrent-through auxiliary contacts 72 oncircuit breaker 4, trip coil 8,conductor 73, contacts 74'and (.5 of change-over switch 15, conductor76, contacts 85 of relay-'18, con

ductor 51, contacts 42of relay 12 to the other side of the controlsource. Thecircu-it breaker 4 by closing its contacts 47 whenit openscompletes the heretofore described circuit for the hesitating controlrelay 20 to'effec'tf the closing of the circuit breaker 5. I

' If the circuit breaker 4 should be closed at any time when theemergency source1is-de energized and the preferred source'2 isenejr'gized'a circuit is completed forthe-tripcoil 8 as soon as the relay "12closes its contacts-'42.

This circuit is from one side of-a suitable,

source of control current through auxiliary cont-acts 72 on circuitbreaker 4-,"tri'p-coil 8.,

conductor 73, c ontacts.74"and 75' o"f'change.

over switch 15, conductor76, conta'cts'86fof voltage relay'll conductor5 1,"c ontacts"42 of; relay 12to' the other side of'the control source.

The closing of the circuitbreaker then effected'by the relay 20thecircuit of which is completed by the circuit breaker 4closi'ni itsauxiliary contacts 47 as heretofore des'cri ed, If at any time anexcessive overload'occllrs on the load circuit3so'. that the overloadrelay 23 is'sufiiciently energized'to close its contacts 27 and 28, acircuit is completed'for the trip 1 coil of whichever circuit breaker isclosed and the coil of thelockout relay 2 6. Thelockout relay 26 byopening its contacts 45 and 62 prevents anyifurther automatic closing ofthecircuit breakers until the relay 26 isreset by hand.

If it is desired to have the source 1 as the preferred source,thechange-over switch 15 is placed in its right-hand position. The

voltage relaylt) and its associate time-relay 12 are thenconnected'across the secondary of the transformer 21 by contacts'36 and87 of the change-over switch and the voltage relay 11 and its. associatetime-relay 13 are connected across the secondary of the" transformer 22by contacts 33 and 3701'. the change- I over switch. The conductor 59 isconnected to the conductors 73 and 48 by contacts58 and 88 and contacts67 and 49 respectively of the change-over switch so that time-relay 13controls the circuit of thejtrip coil 8 of the circuit breaker 4associated with the source 1 which is now the preferred source and thecircuit of the'hesitating control relay 20 of the emergency circuitbreaker 5. The conductor 71 is connected to conductor 63 by contacts and90 of the change-over switch s o that synv chronizing relay 16 controlsthe vcircuit ofhesitating control rela 19 associated with the preferredsource 1. he conductor 76 is con-i nected to the conductor 5 6,bycontacts and 91 of the change-over switch so that trip coil 9 associatedwith the emergency breaker 5jis. controlled by the time-relay 18 and thevoltage relay l1, and the conductor 84 isconnected to theauxiliarycontacts 60 on the circuit breaker 4 by. contacts 83-,and92onthe change-over switch so that the time-relay 18 is, energizedwhenever the preferred circuit breakerd'is openand the contacts of thetime-relay 12 are closed( Since the operation of the system when thechange-over switch. 15 is its, right hand position is similar; to the,heretofore described operation when it isin its l eft= hand p ositi0iLitwill be obyious one skilledin the art and therefore it is believedthat a, detail descripr tionis finnQCQSSflry y;

Whilelhav.e in acco glan'cewith the Patent I Statutes shown anddescribed. my im-"en'tion asiapplied to a particular'system and as em1bodyzing various devices diagrannnatically indicated, changes andmodifications will be ob -i vious tothose skilled in the art, andtherefore aim in the appended claims to co yer all such changes andmodifications as fall within tlietrue spirit andscope of my inventions,I

W11at I claim, as new and I desire to se m e by Letters Patentpf theUnited States,l;i s 1. In combination-,a load circuit, a sourcel of:current connected thereto, another source i of current normallydisconnected from.,sa i d load circuit, means responsive r0 21 redete'r;mined abnormal conditionlof said first mentioned source for effecting.the' disconnection thereof from said load circuit and thecoi nec tionof said other source to said load circuit,

and means responsire to predetermined ,phase relation between thevoltages of sa d sources when, said other source is connccted to saidload circuit for effecting the reconnection of saidfirst mentionedsourceto said load circuit. I I i I 94.3111 combination, a load circuit,afsource of current connected thereto, another SQurco ofcurrent-normally disconnected from said load-circuit, means responsiveto reader-1, mined abnormal condition of said first men tioned sourcefor effecting the disconnection thereof from saidload circuit and theconnection of said other source to saidioad circuit, and meansresponsive ,tQ a predetermined phase relation between thewioltage ofsaid sources when said other source is connected to I said load circuitfor effecting:t-hejreconnection of said first mentioned sourceto saidload circuit an'd the subsequent disconnection of the other source fromsaid load circuit.

3. In combination, a load circuit, a p'r etea e158 dition of saidpreferred source for effecting the opening of said firstmentionedswitching means, means responsive to the openlng of saidfii'st mentionedswitching means for efl'ectingthe closing ofsaid second switching means,and means responsive to apredetermined phase relation het-ween thevoltages of said sources when said second switching means is closed andboth ofsaid sources are energized for reclosingsa d first mentionedswitching means,

. In combination," ioadscircuit a preg ferred sourceof cu rrent,-sw1tch1ng means for connecting s -aid preferredsource. to said loadcircuit, an. emergency source of, current, a secQnd switching means forY connecting said emerge cy and. to said ,1oad;cir.cuit,jme s responsiveto a predetermined abnormal voltage condition of said preferred sourcewhen the voltage cond tions, of.,sa1 d emergency,

source are-normal for effejctingithe opening of said firstmentioned,Iswitching means and the closing of; said sec switching means,

and, means responsiyejo a predetermined phase reiation between thevnl'tages of said sourCcS ,whensaid second switching means s 2 closedand" bothiof said sources are energized for I reclosin'gl said fir,mentioned swit'cl in-g, means and for effecting. the subsequentopeningofsaid'second switching means' 5 lIn combination, a load circuit, avpreferred-source'of current, switching means for connectingsaidprefe'rredsource; to said load circuit,- anemergency; source of current,a second switching: means for connecting said emergency sourgmto saidload circuit, means responsive toa predetermined abnormal 'voltageconditioin of said preferred source when the voltage. conditions of 7said I emergency source are normal foreile cting the opening of saidfirstzmentioncd switching means, means responsive to the 'opening'ofsaid first mentioned,switching me'ans for eifectingthe c losing offs-aidsecond switching means, means repensive to a' predetermincd phaserelation between the ,ibltzigw of said I sources when said secondswitching inc-ans is closed fo'r reclosing saidfirst mentionedsn-"itchin'g' means, and means'rcsponsire to thcreclosing of said firstmentionedswitching means for effecting the opening of the secondswitching means.

G. In combination,aloadcircuit, a sourceof current connected thereto,another source of current normally disconnectedfrom said load'circuit,means responsive to a predeter mined abnormal roltage condition of saidfirst mentioned source. for effecting the disconneetion'thereof fromsaid load circuit and the connectionofsaid other source to said loadcircuit, synchronizing means responsive to a predetermined phaserelation between the voltages of said sources after the voltageconditions of said first mentioned source are restored to normal foreffecting the reconnection of said first mentioned source to said loadcircuit, and means for effecting the disconnection of said other sourcefrom said load cir cuit and the subsequent reconnection of said firstmentioned source to said load circuit when said synchronizing meansfails to effect the reconnection of said first mentioned source within apredetermined time after the voltage conditions thereof are restored tonormal.

7. In combination, a load circuit, a source of current connectedthereto, another source of current normally disconnected from said loadcircuit, means responsive to a predetermined abnormal voltage conditionof said first mentioned source for effecting the disconnection t-hereoffrom said load circuit and the connection of said other source to saidload circuit, synchronizing means responsive to a predetermined phaserelation between the voltages of said sources after the voltageconditions of said first mentioned source are restored to normal foreffecting the reconnection of said first mentioned source to said loadcircuit and the subsequent disconnection of said other source from saidload circuit,

and means for effecting the disconnection of said other source from saidload circuit and the subsequent reconnection of said first mentionedsource to said load circuit when said synchronizing means fails toeffect the reconnection of said first mentioned source within apredetermined time after the voltage conditions thereof are restored tonormal.

8. In combination, a load circuit, a source of current connectedthereto, another source of current normally disconnected from said loadcircuit, means responsive to a predetermined abnormal voltage conditionof said first mentioned source for effecting the disconnection thereoffrom said load circuit and theconnection of said other source to saidload circuit, synchronizing means responsive to a predetermined phaserelation between the voltages of said sources after the voltageconditions of said first mentioned source are restored to normal foreffecting the reconnection of said first mentioned source to said loadcircuit, and means for effecting the disconnection of said other sourcefrom said load circuit and the subsequent reconnection of said firstmentioned source to said load circuit when the voltage condition of saidother source becomes abnormal while supplying current to said loadcircuitand the voltage conditions of said first mentioned source aresubsequently restored to normal.

9. In combination, a load circuit, a source of current connectedthereto, another source of current normally disconnected from said loadcircuit, means responsive to a predetermined abnormal voltage conditionof said first mentioned source for effecting the disconnection thereoffrom said load circuit, synchronizing means responsive to apredetermined phase relation between the voltages of said sources afterthe voltage conditions of said first mentioned source are restored tonormal for effecting the reconnection of said first mentioned source tosaid load circuit and the subsequent disconnection of said other sourcefrom said load circuit, and means for effecting the disconnection ofsaid other source from said load circuit and the subsequent reconnectionof said first mentioned source to said load circuit when the voltageconditions of said other source become abnormal while supplying currentto said load circuit and the yoltage conditions of said first mentionedsource are subsequently restored to normal.

10. In combination, a load circuit, a plurality of sources of currentadapted to supply current to said circuit, means for selecting differentsources as the preferred source, means responsive to a predeterminedabnormal condition of the selected source for effecting thedisconnection thereof from the said load circuit when it is beingsupplied thereby and the connection of another of said sources to saidload circuit, and means responsive to a predetermined phase relationbetween the voltages of said selected source and said other source whensaid other source is connected to said load circuit for effecting thereconnection of said first-mentioned source to said load circuit.

11. In combination, a load circuit, two sources of current for said loadcircuit, means for selecting either of said sources as the preferredsource, voltage responsive means controlled by said selecting means sothat it is responsive to which ever source is the preferred source,means controlled by said voltage responsive means for effectin thedisconnection of the preferred source from the load circuit and theconnection of said other source to said load circuit when said preferredsource is supplying current to said load circuit and a predeterminedabnormal voltage condition occurs on said preferred source, and meansresponsive to a predetermined phase relation between the voltages ofsaid sources when said other source is connected to said load circuitfor effecting the reconnection of said first-mentioned source to saidload circuit and the subsequent disconnection of said other source fromsaid load circuit.

In witness whereof, I have hereunto set my hand this 27th day of April,1927.

ARVID E. ANDERSON.

